Hydraulic cylinders have been used for the actuation of valves for many years. These types of cylinders are especially useful in positioning valves, such as those used in fluidized catatylic cracking units ("FCCU") applied to the refining of petroleum products. The conical plug valves therein utilized are exposed to a very severe service environment, and exposure and intrusion of caustic materials, such as platinium laden silica catalysts and similar particulates, often result in significant damage to the operating piston rods of such hydraulic cylinders. Further, rod bearing assemblies of prior systems have had surface lengths less than the rod diameter, which has been found in accordance with the present invention to provide insufficient support from misalignment and sideloading. Moreover, the piston rods of prior systems have not been properly wetted by the hydraulic fluid. This leads to galling and scratches in the rod surface which leads to seal failure.
If for any reason the bearing gland should fail, its replacement often required the entire hydraulic cylinder to first be removed from service. In the context of a FCCU, this is a dangerous and expensive operation. Moreover, the very possibility of failure is critical, as any leaking hydraulic fluid creates an extremely hazardous event. With a flash point of 325.degree. F. and the surrounding processing lines having skin temperatures sometimes exceeding 600.degree. F., the risk of fire (and potential explosion of the entire FCCU) is not trivial. Also, the hydraulic fluid, at elevated temperatures given this particular environment, creates a direct hazard for repair crews. Moreover, the leakage of hydraulic fluid, even in relatively small amounts (i.e., one gallon) is now an event which must be reported to the United States Environmental Protection Agency. Thus, solutions were sought to end the dangers caused by leakage arising from the failure of bearing glands and for a bearing gland which is durable, easy to replace in service, and effective in protecting the internal components of the hydraulic cylinder.